Preheat your oven to 425°F (220°C). Toss the halved Brussels sprouts with 1 tablespoon of olive oil, salt, and pepper. Spread them cut side down on a baking sheet and bake for about 20–25 minutes until golden brown and crispy.
Heat the remaining tablespoon of olive oil in a large skillet over medium heat. Add the dried red chili peppers, minced garlic, ginger, and the white parts of green onions. Sauté for 1–2 minutes until fragrant.
Stir in tamari sauce, rice vinegar, keto brown sugar substitute, and sesame oil into the skillet. Let it simmer for about 2–3 minutes. If using xanthan gum, whisk it in now.
Add the roasted Brussels sprouts into the skillet with the sauce. Gently toss to coat evenly and cook for another minute or two until glazed.
Transfer the Kung Pao Brussel Sprouts to a serving dish and garnish with green onion tops and roasted peanuts if desired. Serve hot.